По заявкам телезрителей :)
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.Random;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
public class Simulation {
private static final Random globalRandom = new Random(System.currentTimeMillis());
public synchronized int getRandomIntInRangeEnclosed(int min, int max){
return globalRandom.nextInt((max - min + 1) + min);
}
private final static int CUSTOMER_NUMBER = 3000;
private final static int DESK_NUMBER = 6;
public final int ITEM_DURATION_S_MIN = 3;
public final int ITEM_DURATION_S_MAX = 8;
public final CustomerFactory customerFactory = new CustomerFactory(this, CUSTOMER_NUMBER);
public final ArrayList<DeskReport> results = new ArrayList<DeskReport>(DESK_NUMBER);
public void perform(){
ExecutorService executor = Executors.newFixedThreadPool(DESK_NUMBER);
for (int i = 1; i <= DESK_NUMBER; i++) {
executor.submit(new Desk(this, i));
}
executor.shutdown();
try {
executor.awaitTermination(20, TimeUnit.SECONDS);
} catch (InterruptedException ex) {
ex.printStackTrace();
}
}
public void printResult(){
int maxTimeS = 0;
int maxItems = 0;
int maxCustomers = 0;
int minItems = Integer.MAX_VALUE;
int minCustomers = Integer.MAX_VALUE;
for(DeskReport r : results){
if(r.getSpentTime() > maxTimeS){
maxTimeS = r.getSpentTime();
}
if(r.getSoldItemCount() > maxItems){
maxItems = r.getSoldItemCount();
}
if(r.getSoldItemCount() < minItems){
minItems = r.getSoldItemCount();
}
if(r.getServedCustomerCount() > maxCustomers){
maxCustomers = r.getServedCustomerCount();
}
if(r.getServedCustomerCount() < minCustomers){
minCustomers = r.getServedCustomerCount();
}
}
Date date = new Date(maxTimeS * 1000L);
DateFormat formatter = new SimpleDateFormat("HH:mm:ss");
String dateFormatted = formatter.format(date);
System.out.println("---------------- RESULTS ----------------");
System.out.println(DESK_NUMBER + " desks served " + CUSTOMER_NUMBER + " customers in " + dateFormatted);
System.out.println("Troughput min ~ max:");
System.out.println(minItems + "\t~\t" + maxItems + " \titems/desk");
System.out.println(minCustomers + "\t~\t" + maxCustomers + "\tcustomers/desk");
}
public static void main(String[] args) {
Simulation sim = new Simulation();
sim.perform();
sim.printResult();
}
}
public class CustomerFactory {
private Simulation simulation;
private int capacity = 0;
public CustomerFactory(Simulation simulation, int capacity){
this.simulation = simulation;
this.capacity = capacity;
}
public synchronized Customer getInstanceWithRandomCapacity(){
if(capacity-- > 1){
return new Customer(this.simulation.getRandomIntInRangeEnclosed(1,20));
} else {
return null;
}
}
}
public class Desk implements Runnable{
private Simulation s = null;
private int deskNo = 0;
private int servedCustomerCount = 0;
private int soldItemCount = 0;
private int spentTime = 0;
public Desk(Simulation s, int deskNo) {
this.s = s;
this.deskNo = deskNo;
}
public void run() {
System.out.println("Desk " + deskNo + " opening...");
Customer c = null;
while ((c = s.customerFactory.getInstanceWithRandomCapacity()) != null) {
servedCustomerCount++;
for(int i=c.getItemCount(); i>1; i--){
soldItemCount++;
spentTime += s.getRandomIntInRangeEnclosed(s.ITEM_DURATION_S_MIN, s.ITEM_DURATION_S_MAX);
}
//get short break after each customer ;)
sleep(Long.valueOf(s.getRandomIntInRangeEnclosed(s.ITEM_DURATION_S_MIN, s.ITEM_DURATION_S_MAX)));
}
s.results.add(new DeskReport(deskNo, servedCustomerCount, soldItemCount, spentTime));
System.out.println("Desk " + deskNo + "\tclosing.\tcustomers " + servedCustomerCount + "\titems " + soldItemCount + "\ttime(s) " + spentTime);
}
private void sleep(long ms){
try {
Thread.sleep(ms);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
public class DeskReport {
private int deskNo = 0;
private int servedCustomerCount = 0;
private int soldItemCount = 0;
private int spentTime = 0;
public DeskReport(int deskNo, int servedCustomerCount, int soldItemCount, int spentTime){
this.deskNo = deskNo;
this.servedCustomerCount = servedCustomerCount;
this.soldItemCount = soldItemCount;
this.spentTime = spentTime;
}
public int getDeskNo() {
return deskNo;
}
public int getServedCustomerCount() {
return servedCustomerCount;
}
public int getSoldItemCount() {
return soldItemCount;
}
public int getSpentTime() {
return spentTime;
}
}
public class Customer{
private int itemCount = 0;
public Customer(int itemCount){
this.itemCount = itemCount;
}
public int getItemCount(){
return this.itemCount;
}
}
Симуляция примитивнейшая, демонстрирует скорее работу планировщика потоков, нежели магазина. Но если ее развить: смоделировать неравномерное "поступление" покупателей в магазин, очередь к кассам, случайный выбор кассы покупателем и т.д., можно узнать много интересного о работе магазинов. А пока, чтоб не было совсем уж бессмысленно, считается хоть какая-то примитивная статистика.
